The effect of metformin treatment on gastric acid secretion and gastrointestinal hormone levels in normal subjects.

Gastric acid secretion and gastrointestinal hormone levels were measured in healthy non-diabetic subjects after metformin treatment (1.5 g/day). The maximum acid output was increased from 15.7 +/- 3.9 mmol/h (mean +/- SEM) to 30.0 +/- 7.1 mmol/h (p < 0.05) and the peak acid output was increased from 16.4 +/- 4.1 mmol/h to 31.7 +/- 7.2 mmol/h (p < 0.05) after two weeks treatment. Serum insulin, gastric inhibitory polypeptide and secretin levels were normal. After treatment for one week, however, there was a significant increase in fasting vasoactive intestinal peptide (VIP) from 83 +/- 6 ng/1 to 102 +/- 9 ng/1 (p < 0.02) and in stimulated VIP from 58 +/- 5 ng/1 to 79 +/- 5 ng/1 (p < 0.05). Stimulated glucagon-like immunoreactivity (GLI) was also increased from 82 +/- 10 ng/1 to 174 +/- 24 ng/1 (p < 0.01) after one week's treatment. It is suggested that metformin acts as a weak histamine agonist.